The present invention relates to a device for the elimination of disturbances caused by static electricity in liquid scintillation counting. In the liquid scintillation counting, a sample bottle is shifted into a measurement chamber inside a radiation protective device and nuclear fissions occurring in the sample bottle are measured by a liquid scintillation counter in the chamber.
The liquid scintillation counter measures the nuclear fissions occurring in the sample bottle, whose energy is liberated as .alpha.-, .beta.- or .gamma.-radiation. In addition to the substance to be measured and a solvent, the sammple bottle contains a primary scintillator liquid, which converts the energy into the ultraviolet range, and a secondary scintillator liquid, which converts the energy into a discharge of a longer wavelength, near visible light.
Sample bottles charged with static electricity, as a result of rubbing, for example, are a common phenomenon disturbing liquid scintillation counting. A discharge of the produced electrostatic charges during the liquid scintillation counting may increase the background by several orders. Furthermore, the pulses obtained do not follow the law of random coincidence, so that the use of either mathematical monitoring or delayed coincidence is impossible.
A charge on the sample block may be eliminated by a separate treatment such as, for example, by washing or wiping the bottle with a piece of cloth moistened in spirit, or spraying an anti-static agent onto the sample bottle. However, these procedures constitute additional steps of treatment of the sample, so that their use is not desirable in practice.
Mechanical solutions in the measurement device such as, for example, the use of specific materials, the geometric configuration of the measurement chamber, etc, are difficult to optimize and are frequently insufficient.